resolver.c

   1 /* Name resolution using adns */
   2
   3 #include <errno.h>
   4 #include "secnet.h"
   5 #include "util.h"
   6 #ifndef HAVE_LIBADNS
   7 #error secnet requires ADNS version 1.0 or above
   8 #endif
   9 #include <adns.h>
  10 #include <arpa/inet.h>
  11 #include <string.h>
  12
  13
  14 struct adns {
  15     closure_t cl;
  16     struct resolver_if ops;
  17     struct cloc loc;
  18     adns_state ast;
  19 };
  20
  21 struct query {
  22     void *cst;
  23     int port;
  24     struct comm_if *comm;
  25     resolve_answer_fn *answer;
  26     adns_query query;
  27 };
  28
  29 static resolve_request_fn resolve_request;
  30 static bool_t resolve_request(void *sst, cstring_t name,
  31                               int port, struct comm_if *comm,
  32                               resolve_answer_fn *cb, void *cst)
  33 {
  34     struct adns *st=sst;
  35     struct query *q;
  36     int rv;
  37     const int maxlitlen=
  38 #ifdef CONFIG_IPV6
  39         ADNS_ADDR2TEXT_BUFLEN*2
  40 #else
  41         50
  42 #endif
  43         ;
  44     ssize_t l=strlen(name);
  45     if (name[0]=='[' && l<maxlitlen && l>2 && name[l-1]==']') {
  46         char trimmed[maxlitlen+1];
  47         memcpy(trimmed,name+1,l-2);
  48         trimmed[l-2]=0;
  49         struct comm_addr ca;
  50         ca.comm=comm;
  51         ca.ix=-1;
  52 #ifdef CONFIG_IPV6
  53         socklen_t salen=sizeof(ca.ia);
  54         rv=adns_text2addr(trimmed, port, adns_qf_addrlit_ipv4_quadonly,
  55                           &ca.ia.sa, &salen);
  56         assert(rv!=ENOSPC);
  57         if (rv) {
  58             char msg[250];
  59             snprintf(msg,sizeof(msg),"invalid address literal: %s",
  60                      strerror(rv));
  61             msg[sizeof(msg)-1]=0;
  62             cb(cst,0,0,0,msg);
  63         } else {
  64             cb(cst,&ca,1,1,0);
  65         }
  66 #else
  67         ca.ia.sin.sin_family=AF_INET;
  68         ca.ia.sin.sin_port=htons(port);
  69         if (inet_aton(trimmed,&ca.ia.sin.sin_addr))
  70             cb(cst,&ca,1,1,0);
  71         else
  72             cb(cst,0,0,0,"invalid IP address");
  73 #endif
  74         return True;
  75     }
  76
  77     q=safe_malloc(sizeof *q,"resolve_request");
  78     q->cst=cst;
  79     q->comm=comm;
  80     q->port=port;
  81     q->answer=cb;
  82
  83     rv=adns_submit(st->ast, name, adns_r_addr, 0, q, &q->query);
  84     if (rv) {
  85         Message(M_WARNING,
  86                 "resolver: failed to submit lookup for %s: %s",name,
  87                 adns_strerror(rv));
  88         free(q);
  89         return False;
  90     }
  91
  92     return True;
  93 }
  94
  95 static int resolver_beforepoll(void *sst, struct pollfd *fds, int *nfds_io,
  96                                int *timeout_io)
  97 {
  98     struct adns *st=sst;
  99     return adns_beforepoll(st->ast, fds, nfds_io, timeout_io, tv_now);
 100 }
 101
 102 static void resolver_afterpoll(void *sst, struct pollfd *fds, int nfds)
 103 {
 104     struct adns *st=sst;
 105     adns_query aq;
 106     adns_answer *ans;
 107     void *qp;
 108     struct query *q;
 109     int rv;
 110
 111     adns_afterpoll(st->ast, fds, nfds, tv_now);
 112
 113     while (True) {
 114         aq=NULL;
 115         rv=adns_check(st->ast, &aq, &ans, &qp);
 116         if (rv==0) {
 117             q=qp;
 118             if (ans->status!=adns_s_ok) {
 119                 q->answer(q->cst,NULL,0,0,adns_strerror(ans->status));
 120                 free(q);
 121                 free(ans);
 122             } else {
 123                 int rslot, wslot, total;
 124                 int ca_len=MIN(ans->nrrs,MAX_PEER_ADDRS);
 125                 struct comm_addr ca_buf[ca_len];
 126                 for (rslot=0, wslot=0, total=0;
 127                      rslot<ans->nrrs;
 128                      rslot++) {
 129                     total++;
 130                     if (!(wslot<ca_len)) continue;
 131                     adns_rr_addr *ra=&ans->rrs.addr[rslot];
 132                     struct comm_addr *ca=&ca_buf[wslot];
 133                     ca->comm=q->comm;
 134                     ca->ix=-1;
 135                     switch (ra->addr.sa.sa_family) {
 136                     case AF_INET:
 137                         assert(ra->len == sizeof(ca->ia.sin));
 138                         break;
 139 #ifdef CONFIG_IPV6
 140                     case AF_INET6:
 141                         assert(ra->len == sizeof(ca->ia.sin6));
 142                         break;
 143 #endif /*CONFIG_IPV6*/
 144                     default:
 145                         /* silently skip unexpected AFs from adns */
 146                         continue;
 147                     }
 148                     memcpy(&ca->ia,&ra->addr,ra->len);
 149                     wslot++;
 150                 }
 151                 q->answer(q->cst,ca_buf,wslot,total,0);
 152                 free(q);
 153                 free(ans);
 154             }
 155         } else if (rv==EAGAIN || rv==ESRCH) {
 156             break;
 157         } else {
 158             fatal("resolver_afterpoll: adns_check() returned %d",rv);
 159         }
 160     }
 161
 162     return;
 163 }
 164
 165 /* Initialise adns, using parameters supplied */
 166 static list_t *adnsresolver_apply(closure_t *self, struct cloc loc,
 167                                   dict_t *context, list_t *args)
 168 {
 169     struct adns *st;
 170     dict_t *d;
 171     item_t *i;
 172     string_t conf;
 173
 174     st=safe_malloc(sizeof(*st),"adnsresolver_apply");
 175     st->cl.description="adns";
 176     st->cl.type=CL_RESOLVER;
 177     st->cl.apply=NULL;
 178     st->cl.interface=&st->ops;
 179     st->loc=loc;
 180     st->ops.st=st;
 181     st->ops.request=resolve_request;
 182
 183     i=list_elem(args,0);
 184     if (!i || i->type!=t_dict) {
 185         cfgfatal(st->loc,"adns","first argument must be a dictionary\n");
 186     }
 187     d=i->data.dict;
 188     conf=dict_read_string(d,"config",False,"adns",loc);
 189
 190     if (conf) {
 191         if (adns_init_strcfg(&st->ast, 0, 0, conf)) {
 192             fatal_perror("Failed to initialise ADNS");
 193         }
 194     } else {
 195         if (adns_init(&st->ast, 0, 0)) {
 196             fatal_perror("Failed to initialise ADNS");
 197         }
 198     }
 199
 200     register_for_poll(st, resolver_beforepoll, resolver_afterpoll,
 201                       ADNS_POLLFDS_RECOMMENDED+5,"resolver");
 202
 203     return new_closure(&st->cl);
 204 }
 205
 206 void resolver_module(dict_t *dict)
 207 {
 208     add_closure(dict,"adns",adnsresolver_apply);
 209 }